HomeMy WebLinkAboutOWTS DesignHuddleston-Berry
Eogineering & Testing, LLC
2789 Riverside Parkway
Grand Junction, Colorado 81501
Phone: 970-255-8005
Info@huddlestonberry. com
September 20,2022
Project#02375-0001
Kay Crook
PO Box 1174
Rifle, Colorado 81650
Subject:
Reference
OWTS Design
Parcel 217902400549
Silt, Colorado
Geotechnical Investigation, Parcel 217902400549, Silt, Colorado by Huddleston-
Berry Engineering & Testing,LLC for Kay Crook, July 12,2022-
Dear Ms. Crook,
At your request, Huddleston-Berry Engineering & Testin g, LLC completed design of an Onsite
Wastewater Treatment System (OWTS) for a multi-family residence at Parcel 217902400549 in
Silt, Colorado. The site location is shown on Figure I - Site Location Map. A site plan is
included as Figure 2.
Site Description
Át the time of the investigation, small to large trees occupied the site. The site was generally
sloping down to the south. Site topography is shown on Figure 2. Yegetation consisted primarily
of grasses, weeds, and small to large bushes and trees. The site was bordered to the north, west,
east by vacant lots, and to the south by a residential property.
Subsu rface Investisation
As discussed in the referenced report, the subsurface conditions at the site were fairly consistent.
The test pits encountered 1.0 foot of topsoil above tan, moist, very dense gravel, cobble, and
boulder soils in a silty sand matrix to the bottoms of the excavations where bucket refusal was
encountered. Groundwater was not encountered in the subsurface at the time of the investigation.
Although groundwater was not encountered during the subsurface investigation, HBET believes
that the seasonal high groundwater elevation is deeper than 8.0 feet below the existing grade at
this site.
The locations of the test pits are shown on Figure 2. Copies of the test pit logs are included in
Appendix A.
Pu'ce1217902400549 Ã#o2375.ooor t'ruÐÐli*gm*;.,lffiostzotzz Kø
Onsite Waste,wnter Treatment Svstem
Tn order În evahrafe the soils for Onsite Wastewafer Treatment, percolation testing was
conducted at the site in accordance with Garfield County regulations. The percolatlon rate ìn the
native soils ranged from l0 to 13 minutes-per-inch. The percolation testing data are included in
Appendix B.
In accordance with Garfield County regulations, a percolation rate of between 5 to 60 minutes-
per-inch is required for soils to be deemed suit¿ble for onsite wastewater treatment. Therefore,
based upon the results of the percolation testing, HBET believes that the native soils are suitable
for onsite wastewater treatment.
In addition to the percolation rate of the subsurface materials, the seasonal high groundwater
elevation is an important factor in determining the suitability of the site for Onsite Wastewater
Treatment Systems. For OWTS suitability, the seasonal high groundwater elevation should be at
least four feet below the bottom of the proposed absorption bed. As discussed previously, HBET
believes that the seasonal high groundwater elevation is deeper than 8.0 feet below the existing
grade at this site.
Seepage Bed Design
The design of the absorption system generally follows the requirements of the Garfield County
Department of Public Works as outlined in the Garfield County On-Site \lastewater Treatment
System Regulations, effective July 2018. The proposed construction at the site is anticipated to
include a duplex consisting of two bedrooms each. Therefore, the design will consider a total of
four bedrooms.
Based upon the soil percolatìon rate and visual-tactile classifïcation of the soils, a Long-Term
Acceptance Rate (LTAR) of 0.6 will be utilized for the absorption field design. Infiltrator
Systems Quick4 Standard Chambers are proposed. The daily flow of the sewage disposal system
is calculated below, and a plan and profile of the absorption system are shown on Figure 3.
Average Daily Flow: (8 persons)(75 GPD/person)
:600 GPD
Soil Treatment Area: (600 GPD / 0.6;: 1,000 Square Feet
Adjusted Soil Treatment Area : (1,000 SFXl.0X0.7) : 700 Square Feet
# of Quick4 Chambers : (700 I 12¡ =59 Chambers; Use 60 Chambers
System Instøll¡tlÍtm
The installation of the septic tank, plumbing lines, lnfiltrators, etc. should be completed in
accordance with the Garfield County On-Site Wastewater Treatment System Regulations and
Infiltrator Systems, Inc. specifications. In addition, the following construction procedures are
recommendecl:. The septic tank and distribution box should be placed level over native soils that have
been scarified to a depth of 8 to 12 inches, moisture conditioned, and recompacted to
a minimum of 95% of the standard Proctor maximum dry density, within +2%o of
optimum moisturc contcnt. Howcvcr, up to 3-inchcs of washcd rock or pipc bcdding
22:\2008 ,{LL PROJECTS\02375 - Kay Cr@k\02375-0001 Paræl 21 7902400549V0o - Cæ\02375-0001 I-R092022.d@
Parcel 217902400549
#0237s-0001
09no/22
Hu.ldleston-BerÍ
Eng¡r.rin! ú Trs¡n& LLC
passing the l-inch sieve may be used as a leveling course under the septic tank and/or
distribution box.r The bottoms of trenches and backfill around the septic tank and distribution box
which will support sewer or effluent lines should be compacted to at least 90 percent
of the standard Proctor maximum dry density, within t2o/o of optimum moisture
content. Pipe bedding should have a maximum particle size of l-inch.. Vehicular or heavy equipment traffrc and placement of structures should not encroach
within 10 feet of the septic tank or distribution box.
Inspectìon Schedule
Huddleston-Bery Engineering & Testing LLC should be retained to monitor the construction of
the OWTS. The following schedule of observation and/or testing should be followed:r Observe the absorption bed excavation prior to placement of Infiltrator chambers.r Observe placement of the septic tank, distribution box, and all connecting sewer and
effluent lines prior to backflrll. Veriff proper fall between inverts.r Observe and veri$' installation of the absorption bed prior to placement of cover and
backfill.
In conformance with Garfield County regulations, HBET will be required to provide the Garfield
County Health Department with documentation certifying that the OWTS was placed in
conformance to the plan and profile and Garfield County regulations.
General Notes
The OWTS design was based upon the results of the subsurface investigation and on our local
experience. The design is valid only for the proposed construction.
We are pleased to be of service to your project. Please contact us if you have any questions or
comments regarding the contents of this report.
Respectfully Submitted:
Huddleston-Berry Engineering and Testing' LLC
Michael A. Berry, P.E.
Vice President of Engineering
J
0103
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FIGURES
Site Location
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FIGURE 1
Location Map
r-1(50'IJWATER LINEREPAR!}AREA \HOMEDRIVEWAY\SCALE: 1" = 40'C.I. = 5 FT----=-- -MINSEPTIC TANK(S)WITH MINIMUM1,250 GALLONCAPACIÏY-60'MrN)/'|_---4 Af-IIIIII REPAIR\ nnenIIIIIIIIIIIIIIIIII-lE)*NOE| IcilsnFACTORBÐ WILNSC.4.LË: 1": 160' TEST PITProject No.: 02375-0001Date: 09120122By: MABHuddleston-Berr-vEngineering & Testing, LLC2789 Riverside ParkwayGrand Junction, CO 81501
Project No.: 02375-0001Date: 09120122By: MABHuddleston-Berr-vEngineering & Testing, LLC2789 Riverside ParkwayGrand Junction, CO 81501PARCEL#217902400549FIGURE3-SEPTICSYSTEMDETAiLSDETAIL AREASCALE: 1" =20'K-ttN4.INCH DLAMETER SE1VER ANDEFFLUENT PIPE MEËTING ASTM DI785.SCHEDULE 40 OR SDR 35NFILTRÁ TOR SYSTEIVÍ S QUICK4STANDAì.D CHAMBÊ,RSINSPECTiON PORTSSEPTIC TANK(S)WTTH MINIMUMI,250 GALLONCA?ACITY+INCH ÐL{METER SEWER ANDEFFLUENT PIPE MEETING ASTIvf DISCHEDULE 40 OR SDR 35TERLINE++usE slvEEP 90'S ORTWO 45'S AT 90DEGREE BENDS'I\LIZED SYSTEM PROFILE¡lt¡T ToSCALERISEFS (AS NECESSARY)THAT LIDS Æi A- JRFINISHEI} GRAIEESl.2.0 FT.t.0 Ff tâX,1.0 FT MIN.TANKRALIZED BED PROFILENIIT TtISCALEINFILTRATOR SYSTEMS QI].ICK4STÀ\DAFD3R OTHER. SI,].ITABLESURFACEìIATERNEEDLE PLNCHED, GEOTEXTILEFABR:C IT&4EDIATELY ABOVE CHAMBERS6 FT MIN BETWEEN IRENCHESI}¡D{IMUM SETBACKS(tNlrs=rÐ!0¿5INFILÏRAÏOR OUICK4STANDARÐ CHAMBERSt010¡0L¡I{E! DIf€Í{l0ät0Fr¡t¡EtFELIS505050LâIE, sIREAI1,utl-¡t{ED lttcH45I¡VELL¡NG35UCCUP¡EDH.¡TLD'NGt0¡!t0PiæERIY UI{ETILD BE IN.{CCORDANCE IV:TËG,IRFiELD COUNTY O\ryTS REGULATIONS
APPENDIX A
Typed Test Pit Logs
vgFTC}{zc=EmvoÈJ(¡,\¡('lôoootrFtzx0,ooxs^Þtfr¡5: viaq:- tú ã9=E.øà5 ¿ù OQsa?uÔ Àw-3@E^ ^Y!¿æ<0e;E ã'oö:1_oaR.ÈôEqri|-o!agnto5oÞ-{ız!voLmo-{z3mÞãôñ\¡(ooÀ)åoo('tå(o4{mcn{T{zc=@m7{P¡l,6)mo12otn(/,5oomÞEU'C]lrlxC)Ioz3m¿oct-tıo-J@n,o-ÕomxoÞozooz{ÃÞo{ovrT'4..DE{lfl@-{Þvmoê(r!rNto¿fn()xmoTEoo=Efll{nc},ooìlúfmÐmxl)IozÞ2goìlmxoÞÞızl".rIIIoo77oo>.r={ooJ<mñtEq*l8EsÞ !11Éi?-{ızo.¿{mvt{:o{îâNmDEPTH(ft)GRAPHICLOG-lm7trgmU)c)7!+ozSAMPLE TYPENUMBERRECOVERY %(RAD)BLOWCOUNTS(N VALUE)POCKET PEN,(ts0DRY UNITWT(pcOMOISTURECONTENT (o/o)+r-'l=msu=@ørmnoFINES CONTENT(Y")LIOUIDLIMITPLASTICLIMITPLASTICITYINDEXi ll-. f-. ¡s.' l',ì . tà. .1ç . 1{..1SL.r\ . t/_, ,\ .t/_U,a,ot(aÉ.JoðA)ı'o+o-{tØornoctt,ql-ooo@odoıÊ)rú(t¡-nootc)ıo(atll.É@<t-om.? (/,ooEã9øct-omÃØ=g)gØzo3A'xıc)tc'.-ot@oo3ooØ!t0)N¿tt(Do
02375-0001 PARCEL 21 7902400549.GpJUS LAB.GDT'ovet¡o{zc=Emvot\)C,J-.tC¡oooo|-mz{^qtoıotf,\ìl.)IopoôoLI]ù(¡@oûaR"Fìo-g.saFa)!votno5oJoz1t7oLmozÞ=m!Ðãq_..t(ol\)Àoooì5(oa¡ro{m@{.E{zc=wmv{TIN'gomo-nzo{mo5oomUE(ntrmxc)Þ{oz3mI+oc'mxc,ÞIozoozvc)-{onT4.(Dtr,-{mØ-{Þ1mç'o(¡À)--lıctxJ@q,Q-ooo¿moxmç,E(Doo=!mtltoo(JlNIm7mxoÞoz{mztrol1mxc)Þ{ozo.:ovo>,ãttl<ñi-otr''t,/XEiítrÉþ{ozo.?6)7oczom-mız-{lflat,!{(t,NmoDEPTH(fi)GRAPHICLOG{mnrUmg,ovli--{ozSAMPLE TYPENUMBERRECOVERY %(ROD)BLOWCOUNTS(N VALUE)POCKET PEN,(tsÐDRY UNITWT(pc0MOISTUREcoNTENT (%)-t--l=mS¡-l qlØmnoFINES CONTENT(o/o)LIQUIDLIMITPLASTICLIMITPLASTICITYINDEXtl: . È-. r\-- rvj. . t^ .l-t,__ .r\. . PJ .r*ti." .1+ .'u')Ø!)€.foıo¡P.oØIotlU,Ir-$ dqN J(J5 3Fı oo$ ı'mY <ao xo\<fo o_cl@ oc)9 do= o@o lalaiïs¡ ¿r)bÞ'1't a,Õr=9qØ2(]3Exgc)qç@oo3ooaEq)o(Doi+
APPENDIX B
Percol¿tion Testing Results
PERCOLATION TESTING
srP322Huddleston-Berr!'
Eoginccring ô¡ Tc$ting. LLC
Project Name: Parcel217902400549 Location: Silt, CO
Testing Conducted By:
Supervising Engineer:
S. Dinterman
M. Berry
TEST PIT DIMENSIONS
SOIL PROFILE
Test Number:
Top of Hole Depth
Diameter of Hole:
Depth of Hole:
Time
(min.)
Water
Depth
(in.)
Change
(in.)
0 0.25
5 4.125 3.875
10 7 2.875
15 9.125 2.125
20 11 1.875
25 12.5 1.5
30 13.75 1.25
35 15 1.25
40 16 1
45 17 1
50 17.75 0.75
55 18.25 0.5
60 18.75 0.5
10Rate (min/in):
Test Number: 1
Top of Hole Depth: --ı-tnl
Diameter of Hole: 5 (in)
Depth of Hole: 17 (in).
Test Number:
Top of Hole Depth:
Diameter of Hole:
Depth of Hole:
(fi)
(in)
(in)
1-- 0-:b
%
(fi)
(¡n)
(in)
2375
TP-1@
Project No.
Test Pit No.
Date:
Length
(fr)
wdth
(ft)
Depth
(ft)
Water Level Depth (ft)
Depth (ft)Not Encountered
2.5 X
Depth
(fi)Description Remarks
0-0.5 Siltv Sand with Orqanics ffOPSOIL)
0.5-2.5
COBBLES and BOULDERS in a Silty SAND matrix (bldrcbbl), tan,
moist. medium dense
Time
(min.)
Water
Depth
(ín.)
Change
(in.)
0 0.25
5 1.375 1j25
10 2.5 1.125
15 3.75 1.25
20 4.625 0.875
25 5.5 0.87s
30 6j25 0.625
35 6.75 0.625
40 7.375 0.625
45 I 0.625
50 8.375 0.375
55 8.75 0.375
60 9j25 0.375
13
Time
(min.)
Water
Depth
(in.)
Change
(in.)
Average Percolation Rate (min/in)
Rate (min/in)Rate (min/in):